1,720,974 research outputs found
Erythroleukemic cells: neutral sphingomyelinase and differentiation.
No full textL'articolo riguarda il database della ASTON.IT e si riferisce al comportamento della sfingomielinasi neutra durante il processo di differenziazione delle cellule eritroleucemiche
Choline base exchange activity in rat hepatocyte nuclei and nuclear membranes
No full textPrevious investigations have demonstrated the presence of phospholipids as a component of chromatin; however the mechanism of their synthesis, namely if they are synthesized in the nuclei or in the cytoplasm (microsomal fraction), from where they may eventually be transported to the nucleus, has not yet been clarified. The phosphatidylcholine, for example, can be formed, albeit in a limited amount, by an interconversion reaction between bases. The aim of the present research was to ascertain the presence of the enzyme complex responsible for this reaction in hepatocyte nuclei and in isolated nuclear membrane. The incorporation of [14C]-choline in phosphatidylcholine was assayed in microsomes, hepatocyte nuclei, liver nuclei and nuclear membranes of rat liver. The reaction was Ca2+-dependent and the specific activity was higher in microsomes but was present, albeit at a low level, also in nuclei and in nuclear membranes. Possible contaminations were excluded by specific microsomal markers and by the reaction time course. In fact, the nuclear reaction reached the maximum level slowly with respect to microsomes. Since the phosphatidylcholine extracted from the nuclei show an enrichment in unsaturated fatty acids of monoenoic fraction, such as oleic acid, the difference in reaction kinetics has been tentatively explained as due to the phosphatidylcholine fatty acid content. The presence of this base exchange enzyme complex may allow a fast change in chromatin phospholipid composition
Changes In nuclear Phosphatidylcholine-dependent Phospholipase C activity in erythroleukemic cell induced to differentiate.
No full textNo abstract Parte del database dell'ASTON
L'argomento riguarda le variazioni dei fosfolipidi durante il processo di differenziazione delle cellule eritroleucemiche in coltura
Chromatin neutral sphingomyelinase and its role in hepatic regeneration
No full textCeramide acts as a second messenger and modulates many cellular functions. This molecule can be produced by enzymatic digestion of sphingomyelin, a phospholipid which has been shown to be in high concentration in a chromatin phospholipidic fraction. In order to clarify whether chromatin sphingomyelin has a role in this signal transduction pathway, it is necessary to define the sphingomyelin cycle. Neutral sphingomyelinase represents the first step of the cycle. In this paper we demonstrate that sphingomyelinase activity can be detected also in the chromatin of rat hepatocyte nuclei and it increases in relation to the entrance in S phase of hepatocyte after hepatectomy. The enzyme can be distinguished from that present in the nuclear envelope on the basis of optimum pH and Km. The role of the spingomyelin pathway in relation to liver regeneration is discussed
Low levels of serum cholesterol/phospholipids are associated with the antiphospholipid antibodies in monoclonal gammopathy
No full textA decrease in cholesterol blood level, not due to a decrease synthesis by the liver, has been observed in patients suffering from tumors. In this work cholesterol blood was evaluated in patients affected by monoclonal gammopathy who were not subjected to any treatment. The blood of 25 patients were analyzed for protein and lipid content. Patients were divided according to the gamma protein content into three groups, and it was demonstrated that the group with high levels of gamma proteins presented a strong decrease in blood cholesterol and phospholipids. In these patients the presence of antibodies against phospholipids by using cardiolipin and phosphatidylinositol as antigens has also been demonstrated. The antibodies were rare in patients with a low content of gamma proteins and normal level of lipids, but the frequency was more than 80% in patients with low blood lipid levels
Different expression of tyrosine aminotransferase and serine deydratase in rat livers after partial hepatectomy.
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Variation of tyrosine aminotransferase expression during the day in rats of different ages.
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